Using non-precipitating monospecific antibodies as probes of conformation, we are studying structural differences of hemoglobin in solution: Hemoglobin Ao and A2 have been isolated, purified and carbamoylated with Kc14NO. Two specific subpopulations of anti-hemoglobin antibodies have been isolated by affinity chromatography using synthetic peptides corresponding to alpha (129-141) and delta (1-13). The first subpopulation will be used to study conformational changes at the carboyterminus of the alpha chain during oxygenation based on the difference in the binding affinity between C14 oxy and C14 deoxy hemoglobin. Differences will be used to examine mutant and truncated hemoglobins so as to better understand the structural changes occurring during the dynamic transition from the T (deoxy) state to the R (oxy) state. The second subpopulation will be used to measure hemoglobin A2 levels in serum and to differentiate A2 from other normal and mutant hemoglobins.